Patent AU-6429100-A (AU)
Title: Pigments having improved colouristic properties and process for their preparation
Inventor: GRANDIDIER YVES
IPC: G02B5/20
Filed: 2000-06-23
Abstract: Preparation of a pigment comprises: (1) subjecting crude pigment(s) and crystalline inorganic salt(s) in the absence of other constituents to a rotor having a tangential speed of at least 10 m/s, to attain at least 80[deg]C by friction effects; and (2) kneading with an organic liquid and if desired adding additional substances selected from inorganic salts, inert additives and colorants. Independent claims are also included for the following: (a) Converting a crude pigment into an amorphous fine-particled form by step (1). (b) Preparing a pigment by kneading a composition comprising a compound of formula (I), crystalline inorganic salt(s) and an organic liquid. At the beginning of kneading, compound (I) is in amorphous form and the organic liquid contains at least one oxo group in its molecule. The proportion of the organic liquid to the inorganic salt is from 1 ml:6 g to 3 ml:7 g and that of the organic liquid to the overall weight of the inorganic salt and the pigment of formula (I) is 1 ml:2.5 g to 1 ml:7.5 g. (c) A pigment of formula (I) measured in gravure printing with an applied amount after drying of 0.860 g/m 2>, of which the pigment accounts for 0.068 g/m 2>; by printing on white kraft paper. The pigment gives a lightness (L*) not > 48, a chroma (C*) of at least 53 and a hue angle (h) of 295-315, after drying. The printing ink is prepared by (i) dispersing (parts by weight) the pigment (30), aqueous solution (30) containing (wt.%) a dispersing resin (30) dissolved in the solution and isopropanol (7), first with a laboratory dissolver at 6000 rotations per minute (rpm) and 23+- 2[deg]C for 15 minutes and then in a bead mill containing ceramic beads of diameter 1.1 +- 0.1 mm at 6000 rpm and 30+- 10[deg]C for 10 minutes; and (ii) diluting the resulting dispersion with an aqueous solution (900 parts by weight) containing (wt.%) polyacrylate (18) dissolved in the solution and isopropanol (15) in the laboratory dissolver at 6000 rpm and 23 +- 2[deg]C for 15 minutes. (d) A crystalline organic pigment of the quinacridone, anthraquinone, perylene, indigo, quinophthalone, indanthrone, isoindolinone, dioxazine, azo, phthalocyanine or diketopyrrolopyrrole series (preferably 1,4-diketopyrrolo[3,4]-pyrrole, especially C.I. Pigment Red 254 (pigment) of formula (II)) comprising (0-8) wt.% of particles of an average size of 0.01-0.12 mu m, based on the weight of particles of size from 0.01-0.1 mu m. The full width at half maximum of a CuK-alpha radiation X-ray powder diagram is 0-0.68[deg] 2theta . (e) A 50 % dispersion of the pigment of formula (II) in a methacrylic resin. The dispersion is applied as a film of thickness such that the absorption maximum in the area from 400-700 nm has an intensity of 1.0 +- 0.1. The maximum occurs at a wavelength of 556-596 (especially 557 - 565) nm. Preferably, the maximum slope (at the inversion point) on the bathochromic side of the absorption maximum reaches at least 5% change in absorption per 1 nm change in wavelength based on the absorption at the absorption maximum. (f) A printing ink concentrate comprising 1-75 (preferably 5-50, especially 25-40) wt.% of the pigment of formula (I) or (II) present in dispersion in a binder solution. (g) A color filter comprising a transparent, essentially colorless substrate and a layer comprising 1-75 (preferably 5-50, especially 25-40) wt.% of the pigment of formula (I) or (II) dispersed in a high molecular mass organic material. (h) A composition for making color filters comprising (wt.%) the high molecular mass organic material and the pigment of formula (I) or (II) (0.01-40, preferably 1-25, especially 5-10) dispersed in the material. (i) A mass-colored, high molecular mass organic material comprising (wt.%) the pigment of formula (I) or (II) (0.05-70) and the high molecular mass organic material (99.95-30). (j) Coloring high molecular mass organic material in the mass by incorporating the pigment of formula (I) or (II) in it.